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Forest health experts from the University of Arkansas at Monticello have identified brown spot needle blight on loblolly pine in 11 additional counties in Arkansas, bringing the total number of confirmed counties to 25.

Brown spot needle blight is a fungal disease that infects pine needles, leading to premature needle loss, stunted growth and long-term stress that increases a tree’s vulnerability to other pests and pathogens. While it has traditionally been associated with longleaf pine (Pinus palustris), recent observations confirm its spread to loblolly (Pinus taeda) and shortleaf pine (Pinus echinata) as well.

“The infection is characterized by needles forming brown spots with a yellow halo, crown discoloration, and progressive needle damage or loss that can lead to tree death,” said Dr. Laura Sims, director of the Arkansas Forest Health Research Center and associate professor of forest health at UAM. “Historically, in the South, the disease has mainly affected longleaf pine during the grass stage; however, we believe that wind and rainfall events have facilitated the spread of the pathogen to new regions and species of pine.”

Temperature, humidity and rainfall patterns have a large influence on the pathogen’s growth, spread and infection process. Most of the infections occur during the rainy season, particularly from late spring through early summer.

“Rainfall and early winter spore production have been observed at some sites in southeast Arkansas and south-central Louisiana, potentially extending the dispersal period to twice a year,” Dr. Sims said.

Dr. Sims, along with her research technicians and forestry student workers, has been monitoring and identifying outbreaks of brown spot needle blight across the southern region with a focus on Arkansas. The 11 newly identified counties include: Bradley, Calhoun, Clark, Cleveland, Columbia, Dallas, Hempstead, Jefferson, Lafayette, Nevada and Ouachita.

Brown spot needle blight was first confirmed in Arkansas in 2020, with detections in Garland and Saline counties. The disease continued to spread in subsequent years, appearing in Grant, Hot Springs, Howard, Montgomery and Sevier counties in 2021; Pike County in 2022; Ashley, Drew and Lincoln counties in 2023; and Chicot, Perry and Union counties in 2024.

Beyond Arkansas, the disease has also been confirmed on loblolly pine by other experts in Alabama, Florida, Georgia, Louisiana, Mississippi, North Carolina, South Carolina, Tennessee and Texas. The most significant damage, including some tree mortality, has been reported in Mississippi, Arkansas and Louisiana.

Through the Arkansas Center for Forest Health Research, Dr. Sims and her team are continuing to study the pathogen and explore practical, science-based measures that forest landowners can take to help slow the spread of the disease. Her research is being conducted in collaboration with the Arkansas Department of Agriculture, the Louisiana Department of Agriculture and Forestry and the USDA Forest Service.

Forest landowners and managers who suspect brown spot needle blight on their property are encouraged to contact Dr. Sims at simsl@uamont.edu.

Diagnostic samples may also be submitted to the center. Samples should be placed first in a paper lunch sack, then sealed inside a one-gallon plastic bag. Each sample should be clearly labeled with the sample name, date of collection, collector’s name and the location of collection (GPS coordinates if available). Ship samples overnight in a sealed box to:

Dr. Laura Sims

University of Arkansas Division of Agriculture, Forestry

110 University Court #3468

Monticello, AR 71656